package com.simpleframe.util;

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class SimpleCrypto {
	 public static String encrypt(String seed, String cleartext) throws Exception {    
	        byte[] rawKey = getRawKey(seed.getBytes());    
	        byte[] result = encrypt(rawKey, cleartext.getBytes());    
	        return toHex(result);    
	    }    
	        
	    public static String decrypt(String seed, String encrypted) throws Exception {    
	        byte[] rawKey = getRawKey(seed.getBytes());    
	        byte[] enc = toByte(encrypted);    
	        byte[] result = decrypt(rawKey, enc);    
	        return new String(result);    
	    }    
	   
	    private static byte[] getRawKey(byte[] seed) throws Exception {    
	        KeyGenerator kgen = KeyGenerator.getInstance("AES");    
	        SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");    
	        sr.setSeed(seed);    
	        kgen.init(128, sr); // 192 and 256 bits may not be available    
	        SecretKey skey = kgen.generateKey();    
	        byte[] raw = skey.getEncoded();    
	        return raw;    
	    }    
	   
	        
	    private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {    
	        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");    
	        Cipher cipher = Cipher.getInstance("AES");    
	        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);    
	        byte[] encrypted = cipher.doFinal(clear);    
	        return encrypted;    
	    }    
	   
	    private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {    
	        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");    
	        Cipher cipher = Cipher.getInstance("AES");    
	        cipher.init(Cipher.DECRYPT_MODE, skeySpec);    
	        byte[] decrypted = cipher.doFinal(encrypted);    
	        return decrypted;    
	    }    
	   
	    public static String toHex(String txt) {    
	        return toHex(txt.getBytes());    
	    }    
	    public static String fromHex(String hex) {    
	        return new String(toByte(hex));    
	    }    
	        
	    public static byte[] toByte(String hexString) {    
	        int len = hexString.length()/2;    
	        byte[] result = new byte[len];    
	        for (int i = 0; i < len; i++)    
	            result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();    
	        return result;    
	    }    
	   
	    public static String toHex(byte[] buf) {    
	        if (buf == null)    
	            return "";    
	        StringBuffer result = new StringBuffer(2*buf.length);    
	        for (int i = 0; i < buf.length; i++) {    
	            appendHex(result, buf[i]);    
	        }    
	        return result.toString();    
	    }    
	    private final static String HEX = "0123456789ABCDEF";    
	    private static void appendHex(StringBuffer sb, byte b) {    
	        sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));    
	    }    

}
